Vascular dilatation device and method

ABSTRACT

A vascular dilatation device for enlarging a flow passage in an obstruction in a vessel carrying flowing blood. A flexible cylindrical dilatation member having first and second ends is placed in the flow passage in the obstruction. An intermediate portion lies between the first and second ends. The flexible cylindrical dilatation member also has an interior flow passage with a diameter and a longitudinally extending central axis extending therethrough. The diameter of the flow passage is variable with movement of the first and second ends relative to each other along the longitudinally extending central axis from a contracted to an expanded condition. A control mechanism causes relative axial movement between the first and second ends towards each other from an extended position to a contracted position. The control mechanism includes an inner flexible elongate tubular member between the first and second ends of the flexible cylindrical dilatation member. The inner flexible elongate tubular member is sufficiently rigid and causes elongation of the cylindrical dilatation member to decrease its diameter and to advance the cylindrical dilatation member through the obstruction in the vessel while preventing axial contraction of the cylindrical dilatation member.

This is a continuation-in-part of application Ser. No. 08/353,558 filedDec. 9, 1994, now U.S. Pat. No. 5,527,282.

This invention relates to a dilatation device and method utilized toenlarge an obstruction in a vessel, a heart valve or other tubularviscera and particularly to a stenosis in a vessel carrying flowingblood and in which it is desired to maintain the flow of blood.

Heretofore balloon catheters and other devices have been utilized fordilating stenoses in blood vessels. In U.S. Pat. No. 5,034,001 aperfusion catheter is disclosed which is used solely for repairing avessel that has been damaged in an angioplasty procedure. The cathetercarries an expandable cage of spirally-arranged wires and a control wirefor varying the radial expansion of the cage. The expandable cage isused to press a flap which may be obstructing blood flow against thearterial wall to maintain the potency of the artery. During the periodof cage expansion, blood flows through the open weave structure of thecage so that ischemia does not occur distal of the catheter. Theexpandable cage disclosed does not provide a construction in whichsufficient radial forces can be provided to perform an angioplastyprocedure. Therefore, it can be seen that there is need for a new andimproved vascular dilatation device and method which overcomes thesedisadvantages.

In general, it is an object of the present invention to provide avascular dilatation device and method which makes it possible togenerate sufficient radial force to compress the stenosis against avessel wall while allowing free blood flow through the vessel and intoside branches from the vessel.

Another object of the invention is to provide a device and method of theabove character which can be utilized to dilate a vessel for prolongedperiods of time while allowing a perfusion of blood into the vesseldistal of the device and into branches from the vessel.

Another object of the invention is to provide a device and method forvascular dilatation which can conform to the linear curvature of avessel while still providing sufficient radial force to compress thestenosis against the vessel wall.

Another object of the invention is to provide a device and method of theabove character in which an elongate hypotube has been provided in thedevice to enhance pushability and torquability.

Another object of the invention is to provide a device and method of theabove character in which an inner tubular member has been provided toenhance the pushability of the dilatation member of the device.

Another object of the invention is to provide a device and method of theabove character in which a safety ribbon has been provided within theinner tubular member to prevent undue elongation of the inner tubularmember.

Another object of the invention is to provide a device and method of theabove character in which a drug can be provided directly to the regionof the vessel undergoing dilatation.

Another object of the invention is to provide a device and method of theabove character which lends itself to the use of radiocontrast liquidsflowing through the device to establish whether or not adequate bloodflow is occurring through the device during expansion of the device.

Another object of the invention is to provide a device and method of theabove character which permits a rapid exchange system allowing thedilatation catheter to be advanced and withdrawn on a guide wire alreadyin place across the vessel stenosis without the need for long guidewires or extension wires.

Another object of the invention is to provide a device and method of theabove character in which a retractable sheath is utilized to facilitatepassage of the device through a blood vessel and through a stenosis inthe blood vessel without damaging the wall of the vessel.

Another object of the invention is to provide a vascular dilatationdevice and method of the above character in which an expandable memberis provided for dilating a stenosis and which thereafter can bedelivered and left in place as a mechanical expanding, self-expanding orballoon expandable stent.

Additional objects and features of the invention will appear from thefollowing description in which preferred embodiments are set forth indetail in conjunction with the accompanying drawings.

FIG. 1 is a side-elevational view partially in section of a vasculardilatation device incorporating the present invention.

FIG. 2 is a cross-sectional view taken along the line 2--2 of FIG. 1.

FIG. 3 is a cross-sectional view taken along the line 3--3 of FIG. 1.

FIG. 4 is a cross-sectional view taken along the line 4--4 of FIG. 1.

FIG. 5 is a cross-sectional view taken along the line 5--5 of FIG. 1.

FIG. 6 is a cross-sectional view taken along the line 6--6 of FIG. 1.

FIG. 7 is a greatly enlarged view of a portion of the dilatation devicein the expanded state.

FIG. 8 is a partial side-elevational view of another embodiment of avascular dilatation device incorporating the present invention with apart of the device covered by a protective material to prevent damage tothe vessel wall.

FIG. 9 is a partial side-elevational view of another embodiment of avascular dilatation device incorporating the present invention which canbe utilized in conjunction with a rapid exchange technique.

FIG. 10 is a side-elevational view partially in section of anotherembodiment of a vascular dilatation device incorporating the presentinvention which incorporates a retractable sleeve.

FIG. 11 is a side-elevational view of another embodiment of a vasculardilatation device incorporating the present invention in which thedevice can be utilized as a placement device for the dilatation memberso that it can be left in place to serve as a stent.

FIG. 12 is a partial bottom elevation view looking along the line 12--12of FIG. 11.

FIG. 13 is a cross-sectional view taken along the line 13--13 of FIG.11.

FIG. 14 is a side-elevational view partially in section of a vasculardilatation device incorporating another embodiment of the presentinvention.

FIG. 15 is an enlarged cross-sectional view taken along the line 15--15of FIG. 14.

FIG. 16 is an enlarged cross-sectional view taken along the line 16--16of FIG. 14.

FIG. 17 is an enlarged side-elevational view of a portion of the deviceshown in FIG. 14 looking along the line 17--17.

FIG. 18 is a cross-sectional view taken along the line 18--18 of FIG.17.

FIG. 19 is a cross-sectional view taken along the line 19--19 of FIG.16.

FIG. 20 is a cross-sectional view similar to FIG. 19 but showing the useof a braid rather than a coil spring.

FIG. 21 is a greatly enlarged fragmentary view taken along the line19--19 of FIG. 17.

FIG. 22 is a side-elevational view of the distal extremity of the deviceshown in FIGS. 14-18 showing the distal extremity with the dilatationmember in an expanded condition.

In general, the vascular dilatation device of the present invention isused for enlarging an obstruction in a vessel carrying flowing blood. Itis comprised of a flexible cylindrical dilatation member adapted to bedisposed in the obstruction which has first and second ends and anintermediate portion between the first and second ends. The flexiblecylindrical dilatation member also has a flow passage extendingtherethrough with a diameter and a longitudinal central axis. Thediameter of the flow passage is a variable with movement of the firstand second ends relative to each other along the longitudinal centralaxis from a diametrically contracted position to a diametricallyexpanded condition. The flexible cylindrical dilatation member iscomprised of a plurality of flexible elongate elements each of whichextends helically about the longitudinal extending central axis. Aplurality of the flexible elongate elements having a first commondirection of rotation are axially displaced relative to each other andcross a further plurality of the flexible elongate elements also axiallydisplaced relative to each other but having a second common directionopposite to that of the first direction of rotation to form a braidedflexible cylindrical member. The crossing of the flexible elongateelements occurs in an area of contact between the flexible elongateelements. First and second means is provided respectively engaging thefirst and second ends of said flexible cylindrical member for retainingsaid first and second ends in contracted positions. Means is providedfor causing relative axial movement of the first and second ends towardseach other to cause the intermediate cylindrical portion of thecylindrical member to contact longitudinally and to expand diametricallyby causing the flexible elongate elements in the intermediate portion ofthe cylindrical member to move closer to each other expanding thediametric dimensions of the cylindrical member and enlarging theobstruction in the vessel or organ. Flexible elongate elements at thefirst and second ends of the cylindrical member remain contracted aroundand within first and second means and are thereby prevented from movingcloser which maintains spacing between the flexible elongate members sothat blood in the vessel can continue to flow through the first andsecond ends and through the flow passage in the flexible cylindricalmember while the cylindrical member is in engagement with theobstruction in the vessel.

More in particular as shown in FIGS. 1-6 of the drawings, the vasculardilatation device 11 shown therein consists of a first or outer flexibleelongate tubular member 12 having proximal and distal extremities 13 and14 with the flow passage 16 extending from the proximal extremity 13 tothe distal extremity 14. A second or inner flexible tubular member 21 iscoaxially and slidably disposed within the flow passage 16 of the firstor outer flexible elongate tubular member 12 and is provided withproximal and distal extremities 22 and 23 with a flow passage 24extending from the proximal extremity 22 to the distal extremity 23.

A guide wire 26 of a conventional type is adapted to be introducedthrough the flow passage 24 in the inner flexible elongate tubularmember for use in guiding the vascular dilatation device 11 ashereinafter described. The guide wire 26 can be of a suitable size asfor example 0.010"-0.018" and can have a suitable length ranging from150 to 300 centimeters. For example, the first or outer flexibleelongate tubular member 12 can have an outside diameter of 1-3millimeters with a wall thickness of 0.25 millimeters to provide a flowpassage of 1.8 millimeters in diameter. Similarly, the second or innerflexible elongate tubular member 21 can have a suitable outside diameteras for example 1.6 millimeters with a wall thickness of 0.25 millimetersand a flow passage 24 of 1.1 millimeters in diameter. The flexibleelongate tubular members 12 and 21 can be formed of a suitable plasticas for example a polyimide, polyethylene or Nylon.

In accordance with the present invention a flexible cylindricaldilatation member 31 is provided which has a first or proximal end 32and a second or distal end 33 with a central or inner flow passage 34extending from the proximal end 32 to the distal end 33 along alongitudinally extending central axis and has a diameter which is avariable as hereinafter described. The flexible cylindrical dilatationmember 31 is comprised of a plurality of flexible elongate elements orfilaments 36 each of which extends helically about the longitudinallyextending central axis. The flexible elongate elements 36 are formed ofa suitable material which can be utilized in the human blood as forexample stainless steel, Nitinol, Elgiloy™ or certain other plasticfibers. The flexible elongate elements 36 can have a suitable diameteras for example 0.06-0.20 millimeters or can be configured as a flat wireribbon. A plurality of the flexible elongate elements 36 have a firstcommon direction of rotation about the central axis as shown in FIGS. 1and 7 and are axially displaced relative to each other and cross afurther plurality of the flexible elongate elements 36 also axiallydisplaced relative to each other but having a second common direction ofrotation opposite to that of the first direction of rotation to form adouble helix or braided or mesh-like flexible cylindrical member withthe crossing of flexible elongate elements 36 occurring in the area ofcontact between the flexible elongate elements to form openings orinterstices 37 therebetween. Thus the flexible elongate elements 36 forma flexible cylindrical dilatation member 31 which provides a central orinner flow passage 34 which is variable in diameter upon movement of thefirst and second ends of the flexible cylindrical dilatation member 31relative to each other along the longitudinally extending central axis.

Means is provided for constraining the first and second or proximal anddistal ends 32 and 33 of the flexible cylindrical dilatation member 31and consists of a first or proximal collar 41 and a second or distalcollar 42. The first and second collars 41 and 42 are formed of asuitable material such as a polyimide. The first or proximal collar 41has a suitable length as for example 1/2" and is sized so that it canfit over the first or proximal end 32 of the flexible cylindricaldilatation member 31 when it is in a contracted position and over thedistal extremity 14 of the first or outer flexible elongate member 12.In order to ensure that elongate elements or filaments 36 of the firstor proximal extremity 32 are firmly secured to the distal extremity 14of the first or outer flexible elongate member 12, an adhesive can beprovided bonding the first or proximal end 32 to the collar 41 and tothe distal extremity 14 of the first or outer flexible elongate tubularmember 12. The second or distal collar 42 can be of a suitable size andtypically may be slightly smaller in diameter because it need merelysecure the elongate element or filaments 36 of the distal end 33 of theflexible cylindrical dilatation member 31 to the distal extremity 23 ofthe second or inner flexible elongate tubular member 21. An adhesive(not shown) is provided to firmly secure the second or distal end 33 ofthe flexible cylindrical dilatation member 31 between the second ordistal collar 42 and the distal extremity of the inner flexible elongatetubular member 21. In this manner it can be seen that the flexibleelongate cylindrical dilatation member 31 has its proximal end curvedconically inward toward and secured to the distal extremity of the outerflexible elongate tubular member 12 and the second or distal end 33 ofthe flexible cylindrical dilatation member 31 also curves conicallyinward toward and is secured to the distal extremity of the second orinner flexible elongate tubular member 21.

Typically the distance between the first and second collars 41 and 42can range from between 5 to 150 millimeters. Typically the distal end 23of the second or inner flexible elongate tubular member 21 extendsapproximately 30 millimeters beyond the distal extremity 14 of the firstor outer flexible elongate tubular member 12.

It can be seen that by moving the first or outer flexible elongatetubular member 12 and the second inner flexible elongate tubular member21 axially with respect to each other, the first and second ends of theflexible cylindrical dilatation member 31 are moved towards each othercausing the elongate elements or filaments 36 of an intermediate portionof the cylindrical dilatation member between the first and second endsto move closer to each other to cause these flexible elongate elementsto move into apposition with each other and to expand radially theintermediate portion of the cylindrical dilatation member 31 and tocause the diameter of the central flow passage 34 to increase. Theportions of the flexible cylindrical dilatation member 31 immediatelyadjacent the first and second collars 41 and 42 remain restrained by thecollars 41 and 42 causing the flexible elongate elements 36 immediatelyadjacent to the collars 41 and 42 to curve conically toward and remaincrossed and unable to come into close apposition and thereby provideopenings or interstices 37 therebetween which remain relatively constantin shape and size so that blood can flow from the first and second ends32 and 33 through the central or inner flow passage 34 as hereinafterdescribed.

Means is provided in the vascular dilatation device 11 for causingrelative movement between the first or outer flexible elongate tubularmember 12 and the second or inner flexible elongate tubular member 21and consists of a screw mechanism 46. The screw mechanism 46 includes aY-adapter 49 which is provided with a central arm 51 having a lumen 52through which the second or inner flexible elongate tubular member 21extends. The lumen or flow passage 52 is in communication with the lumen16 of outer flexible elongate tubular member 12 and with a flow passage53 in a side arm 54 which is adapted to receive a syringe (not shown) sothat a radiocontrast liquid or a drug can be introduced through the sidearm 54 and into the flow passage 52 in the Y-adapter 49 and thence intolumen 16 of outer member 12. The distal end of screw mechanism 46 isprovided with a fitting 56 with inner lumen 57 (see FIG. 6) into whichthe proximal end 13 of flexible elongate tubular member 12 is seated andheld in place by an adhesive 58 at the distal end of fitting 56. Lumen57 is thereby in communication with flow passage 52 of central arm 51and with flow passage 53 of side arm 54. An O-ring 59 which is adaptedto form a fluid-tight seal with respect to the second or inner flexibletubular member 21 is disposed in the lumen 52 of the central arm 51. Aninteriorly threaded knurled knob 66 is threaded onto an exteriorlythreaded member 67 which is secured to and surrounds the proximalextremity 22 of inner flexible elongate tubular member 21. The knob 66is provided with an inwardly extending flange 68 which seats in anannular recess 69 in the central arm 51. Thus, rotation of the knob 66causes advancement or retraction of threaded member 67 and the second orinner flexible elongate tubular member 21 with respect to the fitting56. Indicia 68 in the form of longitudinally spaced-apart rings 70 areprovided on the member 67 and serve to indicate the distance which thesecond or inner flexible elongate tubular member 21 has been advancedand retracted with respect to the first or outer flexible elongatemember 12.

A Luer-type fitting 71 is mounted on the proximal extremity 22 of theinner elongate flexible tubular member 21 and is adapted to be engagedby a finger of the hand. The guide wire 26 extends through the fitting71 and into the lumen 24 of inner elongate flexible tubular member 21.

It should be appreciated that even though one particular screw mechanism46 has been provided for advancing and retracting the flexible elongatemembers 12 and 21 with respect to each other, other mechanisms also canbe utilized if desired to provide such relative movement.

In order to provide the desired radiopacity for the distal extremity ofthe vascular dilatation device 11 so that it can be observedfluoroscopically during a dilatation procedure, the collars 41 and 42can be formed of a radiopaque material as for example by filling theplastic with radiopaque particles of a suitable material such as bariumor by providing collars containing radiopaque metals, such as tungstenor platinum or a tungsten platinum alloy. Although the flexible elongateelements 36 which comprise the flexible cylindrical dilatation member 31have some radiopacity by being formed of a stainless steel or othersuitable material such as Elgiloy, there normally is insufficientradiopacity for most medical procedures. Therefore to augment theradiopacity of the flexible cylindrical dilatation member 31, radiopaquewire of a suitable material such as platinum can be wound along with theflexible elongate element 36 to provide the necessary radiopacity. Thisoften may be desirable because this would make it possible to ascertainthe position of the flexible cylindrical member and its diameter as itis expanded and retracted between a minimum contracted position and amaximum expanded position by relative movement between the distalextremities of the first or outer flexible elongate member 12 and thesecond or inner flexible elongate tubular member 21. The use of thehelical wraps of platinum does not significantly interfere with thegeneral mechanical properties of the flexible cylindrical dilatationmember 31 desired in connection with the present invention.Alternatively, the flexible elongate elements 36 may be plated with aradiopaque metal such as platinum or gold to enhance their radiopacity.Alternatively, the flexible elongate elements may be comprised of hollowwires, the central core of which may be filled with radiopaque metalssuch as tungsten, gold or platinum or with compound salts of highradiopacity.

Operation and use of the vascular dilatation device 11 may now bebriefly described as follows. Let it be assumed that the patient whichthe medical procedure is to be performed utilizing the vasculardilatation device 11 has one or more stenoses which at least partiallyocclude one or more arterial vessels supplying blood to the heart andthat it is desired to enlarge the flow passages through these stenoses.Typically the vascular dilatation device 11 would be supplied by themanufacturer with the flexible cylindrical dilatation member 31 in itsmost contracted position to provide the lowest possible configuration interms of diameter and so that the diameter approximates the diameter ofthe outer flexible elongate tubular member 12. Thus, preferably, itshould have a diameter which is only slightly greater than the tubularmember 12, as for example by 1.0-2.3 millimeters. The first and secondcollars 41 and 42 also have been sized so they only have a diameterwhich is slightly greater than the outer diameter of the outer flexibleelongate tubular member 12. To bring the flexible cylindrical dilatationmember 31 to its lowest configuration, the screw mechanism 46 has beenadjusted so that there is a maximum spacing between the distal extremity23 of the inner flexible elongate tubular member 21 and the distalextremity 14 of the outer flexible elongate tubular member 12. In thisposition of the flexible cylindrical dilatation member 31, the flexibleelongate elements 36 cross each other at nearly right angles so that theinterstices or openings 37 therebetween are substantially square.

With the screw mechanism 46 in this position, the vascular dilatationdevice 11 is inserted into a guiding catheter (not shown) typically usedin such a procedure and introduced into the femoral artery and havingits distal extremity in engagement with the ostium of the coronaryartery. Thereafter, the guide wire 26 can be inserted independently ofthe vascular dilatation device 11. If desired the guide wire 26 can beinserted along with the vascular dilatation device 11 with its distalextremity extending beyond the distal extremity of the vasculardilatation device 11. The guide wire 26 is then advanced in aconventional manner by the physician undertaking the procedure and isadvanced into the vessel containing a stenosis. The progress of thedistal extremity of the guide wire 26 is observed fluoroscopically andis advanced until its distal extremity extends distally of the stenosis.With the flexible cylindrical dilatation member 31 in its diametricallycontracted position, the vascular dilatation device 11 is advanced overthe guide wire 26. The distal extremity 23 of the second or innerflexible elongate tubular member 21 is advanced through the stenosisover the guide wire 26 until it is distal to the stenosis and so thatthe distal extremity 14 of the first or outer flexible elongate tubularmember 12 is Just proximal of the stenosis.

After the flexible cylindrical dilatation member 31 is in a desiredposition in the stenosis, the flexible cylindrical dilatation member 31is expanded from its diametrically contracted position to an expandedposition by moving the distal extremities 14 and 23 closer to each otherby operation of the screw mechanism 46. This can be accomplished byholding one distal extremity stationary and moving the other distalextremity towards it or by moving both distal extremities closer to eachother simultaneously. This movement of the distal extremities 14 and 23causes collars 41 and 42 to move closer to each other and to cause thecentral flexible elongate elements 36 forming the double helix mesh ofthe intermediate portion 31a of the flexible cylindrical dilatationmember 31 to move relative to each other to progressively decrease thevertical crossing angle of the double helically wound flexible elongateelements 36 from approximately 160° to 180° in its extended state to 5°to 20° in its axially contracted state and to progressively change theinterstices or openings 37 from diamond-shaped openings with long axesparallel to the central longitudinal axis of the catheter in itsextended state to substantially square-shaped openings in itsintermediately contracted state to elongate diamond-shaped intersticesor openings with the longitudinal axes extending in directionsperpendicular to the central longitudinal axis with the flexibleelongate elements 36 coming into close apposition to each other while atthe same time causing radial expansion of the flexible cylindricaldilatation member and to progressively increase the diameter of thecentral flow passage 34. The expansion of the flexible cylindricaldilatation member 31 in addition to being viewed fluoroscopically canalso be ascertained by the indicia 68 carried by the threaded member 67.

During the time that the flexible cylindrical dilatation member 31 isbeing expanded, it exerts large radial forces against the stenosis tocompress the stenosis against the wall of the vessel to dilate orenlarge the stenosis so that an increased amount of blood can flowthrough the stenosis. The intermediate portion 31a of the flexiblecylindrical dilatation member 31 when fully expanded is almost a solidtubular mass which has significant radial strength to make possiblecompression of the stenosis against the vessel wall. In addition,because of spring-like properties of the expanded flexible cylindricaldilatation member being comprised of helically wound flexible elongateelements 36, the flexible cylindrical dilatation member 31 can conformto a curve within the blood vessel while still exerting significantradial force to the vessel and to make possible compression of thestenosis without tending to straighten the curve in the vessel whichtypically occurs with standard straight angioplasty balloon systems.Since the ends of the flexible cylindrical dilatation member 31 areconstrained by the proximal and distal collars 41 and 42 the flexibleelongate elements 36 forming the braided mesh of the flexiblecylindrical dilatation member 31 adjacent the distal extremity 23 of theinner elongate flexible tubular member 21 and the distal extremity 14 ofthe outer flexible elongate tubular member 12 under the collars 41 and42, respectively, are held in substantially constant angularrelationship to each other with the vertical crossing angles between 60°and 180° and are unable to come into close apposition with each other.Therefore the interstices or openings 37 adjacent the collars 41 and 42remain open because the flexible elongate elements 36 are unable tochange from their relatively fixed crossed positions. Blood continues toflow through the central or inner flow passage 34 by passing through theopenings 37 in the first or proximal end 32 into the central or innerpassage 34 and out the openings in the second or distal end 33. Thus,blood flow through the vessel is not impeded by the expansion of theflexible cylindrical dilatation member 31. It is believed that the flowthrough the central or inner flow passage 34 can be as great asapproximately 10-100 times than that which can be provided with astandard perfusion balloon.

Since blood flows continuously throughout the dilatation procedure,there is no danger of ischemia occurring. This makes it possible tomaintain dilatation over extended periods of time when desired. Longdilatations extending over periods of time as for example 30-60 minutesmay be utilized if desired. This has an advantage in that in the event aflap or dissection is created during the procedure, sufficient time canbe permitted to pass to create an adhesion of a flap in the stenosis tothe wall of the vessel thereby preventing further dissection and alsoeliminating the need for emergency surgery. The additional dilatationtime is also believed to be advantageous in decreased recoil of thestenosis in the vessel after the flexible cylindrical dilatation member31 has been removed resulting in improved dilation and increased luminaldiameter after the procedure. It is also believed that prolongeddilatation causes decreased cell growth in the regions where dilatationhas taken place which may result in a lower rate of restenosis. Inaddition dilatation with the vascular dilatation device 11 on thepresent invention is particularly advantageous in use with patientswhich have obstructions of a critical nature that cannot even toleraterelatively short periods of dilatation with a balloon without leading toischemia creating permanent damage or shock to the patient.

The open construction of the flexible cylindrical dilatation member 31also serves to prevent blocking off of other vessels branching off fromthe vessel in the region in which dilatation procedures are beingperformed because the blood can flow through the central interstices 38of the flexible cylindrical dilatation member 31.

After the dilatation has been carried out for an appropriate length oftime, the flexible cylindrical dilatation member 31 can be moved fromits expanded position to a contracted position by operation of the screwmechanism 46 in a reverse direction to cause separation of the distalextremities 14 and 23 to thereby cause elongation of the flexiblecylindrical dilatation member 31 with a concurrent reduction indiameter.

After the flexible cylindrical dilatation member 31 has been reduced toits contracted or minimum diameter, the vascular dilatation device 11can be removed along with the guide wire 26 after which the guidingcatheter (not shown) can be removed and the puncture site leading to thefemoral artery closed in a conventional manner.

Although, the procedure hereinbefore described was for treatment of asingle stenosis, it should be appreciated that if desired during thesame time that the vascular dilatation advice 11 is within the guidingcatheter, other vessels of the patient having stenoses therein can betreated in a similar manner merely by retracting the distal extremity ofthe vascular dilatation device 11 from the stenosis being treated andthen advancing it into another stenosis in another vessel in a similarmanner.

Another embodiment of a vascular dilatation device of the presentinvention is shown in FIG. 8 in which the vascular dilatation device 81is very similar to the vascular dilatation device 11 with the exceptionthat the flexible cylindrical dilatation member 86 is constructed in adifferent manner. As shown in FIG. 8, the flexible stainless steelflexible cylindrical dilatation member 86 is formed of flexible elongateelements 36 in the manner hereinbefore described to provide a meshconstruction having proximal and distal extremities 87 and 88 and havingan intermediate portion 86a between the proximal and distal extremities87 and 88 and a central flow passage 89 extending therethrough. Theflexible cylindrical dilatation member 86 differs from the flexiblecylindrical dilatation member 31 in that the outer surface of theintermediate portion 86a between the proximal and distal ends 87 and 88carries and is covered with a radially expandable and contractiblematerial 91 such as a latex, a silicone or a polymeric plastic tube.Such a flexible, expandable and contractible coating can be readilyprovided on the flexible cylindrical member 86 such as by placing thesame on a mandrel (not shown) and masking off the proximal and distalextremities 87 and 88 by a suitable masking material and then dippingthe flexible cylindrical dilatation member into the desired coatingmaterial and then cured in an appropriate manner to bond theexpandable-contractible material 91 to the flexible elongate elements36. The coating material 91 applied covers the flexible elongateelements 36 and fills in the interstices or openings 38 between theelements in the intermediate portion 86a. Alternatively, a tubularsleeve of the appropriate dimensions may be made from the latex siliconeor polymer material and then placed over the intermediate portion 86a ofthe flexible cylindrical dilatation member 86 to leave the proximal anddistal extremities 87 and 88 exposed. These proximal and distalextremities 87 and 88 can be secured to the distal extremities 14 and 23by the collars of 41 and 42 in a manner similar that hereinbeforedescribed.

A vascular dilatation device 81 constructed in this manner can be usedin the same manner as the vascular dilatation device 11 and can beoperated in the same manner. The coated intermediate portion 86a servesto protect the vessel wall from damage and prevents entrapment of tissuebetween the flexible elongate elements 36 as they are being compressedaxially while still permitting the relative free passage of blood intoproximal extremity 87 and into the central flow passage 89 and outdistal extremity 89.

In connection with the present invention and particularly with thevascular dilatation device 11 in which the intermediate portion 31astill has small interstices between the same, the device 11 can beutilized for prolonged drug infusion while the flexible cylindricaldilatation member 31 remains in its expanded state. The drug may beinfused through the side arm 54 which is in communication with the flowpassage 16 in the outer flexible elongate tubular member 12. Since theouter flexible elongate tubular member 12 terminates at the distalextremity 14 or at the first or proximal collar 41, a drug infused intothe side arm lumen 53 will exit at the proximal extremity of theflexible cylindrical dilatation member 31 and also out of the smallinterstices 38 provided between the flexible elongate elements 36 in theintermediate portion 31a and directly into the vessel wall at the siteof vessel dilatation. Thus drug delivery occurs at the site of theangioplasty procedure in a higher concentration than that which may betolerated by systemic administration of the drug. Drugs which may bedelivered with the device 11 include agents to prevent clotting of theblood, such as heparin, TPA, hirudin or various anti-thrombin agents.Alternatively drugs to prevent cell proliferation and restenosis such asangiopeptin or steroids may be administrated by prolonged infusionduring the time that the flexible cylindrical dilatation member is in anexpanded condition.

During the time that the flexible cylindrical dilatation member 31 is anexpanded position, a radiocontrast liquid may be introduced through theside arm 54 which will pass through the flow passage 16 of the outerflexible elongate tubular member 12 into the proximal extremity of theflexible cylindrical dilatation member 31 through the central flowpassage 34 and out the distal extremity 33 through the openings 37therein. The radiocontrast liquid can then be visualized to ascertainflow through the vessel distal of the lesion in which the dilation istaking place. This also makes it possible to assure that the desiredblood perfusion is actually taking place during the dilatationprocedure.

Another embodiment of a vascular dilatation device incorporating thepresent invention is shown in FIG. 9. As shown therein, the vasculardilatation device 101 is constructed in a manner similar to the vasculardilatation device 11 with the exception that it is provided with rapidexchange capabilities. This is accomplished by providing an outerflexible elongate tubular member 102 having a lumen 103 therein and aninner flexible elongate tubular member 106 having a lumen 107 which havethe flexible cylindrical dilatation member 31 secured thereto by theproximal and distal collars 41 and 42. The outer flexible elongatetubular member 102 is provided with a port or opening 111 into thecorresponding lumen 103 and which is 13-60 centimeters from the distalextremity 32 of the flexible cylindrical dilatation member 31. Acorresponding port or opening 112 into corresponding lumen 107 isprovided within the inner flexible elongate tubular member 106. Theseports 111 and 112 are positioned so that when the flexible cylindricaldilatation member 31 is in its expanded position with the distalextremities of the members 102 and 106 being in closest proximity toeach other, the openings 111 and 112 are in registration with eachother. In this position, the vascular dilatation device 111 can beloaded onto the guide wire 16 by advancing the most proximal extremityof guide wire 26 first into lumen 107 of the distal extremity of theinner flexible elongate member 106 and then back through port or opening112 and port 111 which are in registration and out of the flexibleelongate tubular member 102. The flexible cylindrical dilatation member31 is next contracted from its diametrically expanded condition to acontracted condition by moving the distal extremities of outer and innerflexible elongate tubular members 102 and 106 further apart by operationof screw mechanism 46. This procedure is performed while maintaining astable position of the external position of guide wire 26 in a constantposition in relation to port 111. As the distal extremity of flexibletubular member 106 is moved further from the distal extremity offlexible elongate tubular member 102, port 112 will move out ofregistration with port 111 while maintaining guide wire 26 within lumen107 and advancing the distal extremity of the flexible elongate tubularmember 106 along the guide wire 26. In this diametrically contractedstate of the flexible cylindrical dilatation member 31, vasculardilatation device 101 may be advanced along guide wire 26 through theregion of stenosis in the blood vessel and expansion of flexiblecylindrical dilatation member 31 may occur using screw mechanism 46 inthe manner previously described. Once vascular dilatation has beencompleted, flexible cylindrical dilatation member 31 can bediametrically contracted and the vascular dilatation device 101 may beremoved from the blood vessel and the guiding catheter by maintaining astable position of guide wire 26 in relation to the blood vessel andretracting device 101 along guide wire 26 until the distal extremity ofinner flexible member 106 exits the patient's body. The vasculardilatation device 101 may now be rapidly exchanged with another vasculardilatation device 101 as for example one having a flexible cylindricaldilatation member 31 which can be increased to a larger diameter over astandard 150 centimeter length guide wire 26.

Still another vascular dilatation device 121 incorporating the presentinvention is shown in FIG. 10 which is very similar to the vasculardilatation device 11 hereinbefore described with the exception that itis provided with a retractable sheath 126 which extends the entirelength of the outer flexible elongate tubular member 12 and extends overthe flexible cylindrical dilatation member 31 to facilitate passage ofthe flexible cylindrical dilatation member 31 into and through a bloodvessel without damage to the blood vessel by the exposed flexibleelongate elements 36 of the flexible cylindrical dilatation member 31.The retractable sheath 126 extends proximally and extends through thescrew mechanism 46 and is provided with a hook-like member 131 which isslidably mounted in a slot 132 located along central arm 132a of screwadapter 49a. The hook-like member 131 can travel through a distancepermitting retraction of the retractable sheath 126 from over theflexible cylindrical dilatation member 31 so that it can be expanded inthe manner hereinbefore described. If desired, the hook-like member 131can be provided with a portion 131a which extends distally and extendsthrough a hole 137 provided in the knob 66 to prevent rotation of theknob until the hook-like member 131 has been retracted to uncover theflexible cylindrical dilatation member 31. This prevents rotation of thescrew mechanism 46 and expansion of the flexible cylindrical dilatationmember 31 until the retractable sheath 126 has been fully retracted.Thereafter, the dilatation device 121 can be operated in a mannersimilar to that hereinbefore described.

Another vascular dilatation device 151 incorporating the presentinvention is shown in FIGS. 11-13 and consists of a first or outerflexible elongate tubular member 152 which has proximal and distalextremities 153 and 154 with a flow passage 156 extending therebetween.It also consists of a second or inner flexible elongate tubular member157 which has proximal and distal extremities 158 and 159 with a flowpassage 161. There is also provided a third or middle flexible elongatetubular member 162 which has proximal and distal extremities 163 and 164and a flow passage 166 extending therethrough. The third or middleflexible elongate tubular member 162 is coaxially mounted within thepassage 156 of the first or outer flexible elongate tubular member 152which is slidable thereon. The second or inner flexible elongate tubularmember 157 slidably mounted in the flow passage 166 of middle tubularmember 162. The guide wire 26 is adapted to extend through the flowpassage 161 of the second or inner flexible elongate tubular member 157.

A flexible cylindrical dilatation member 31 of the type hereinbeforedescribed is a part of the vascular dilatation device 151 and has itsfirst or proximal extremity 32 retained by slip friction fit and isdisposed in the passageway 156 between the outer surface of the third ormiddle flexible elongate tubular member 162 and the inner surface of thefirst or outer flexible elongate tubular member 152 with the distalextremity 154 of the first or outer flexible elongate tubular member 152terminating just short of the distal extremity 164 of the third ormiddle flexible elongate tubular member 162. The distal extremity 33 ofthe flexible cylindrical dilatation member 31 is also frictionallyretained between a collar or sleeve 171 mounted on the distal extremity159 of the second or inner flexible elongate tubular member 158 andretaining the distal extremity 33 in frictional engagement with thedistal extremity 159 of the second or inner flexible elongate tubularmember 157 to thereby constrain the proximal and distal ends 32 and 33of the flexible cylindrical dilatation member 31 in the mannerhereinbefore described in FIG. 1 with the collars 41 and 42. In order tosecure the distal extremity of the collar 171 to the distal extremity159 of the second or inner flexible elongate tubular member 151, a smallband of adhesive 172 is applied between the collar 171 and the distalextremity 159 with care taken to prevent the adhesive from contactingthe constrained flexible elongate elements 36 of distal end 33.

A y-adapter 176 forms a part of the vascular dilatation device 151 andis provided on the distal extremity. The y-adapter 176 includes acentral arm 177 having a lumen 178 therein and a side and a side arm 179having a lumen 180 therein. The central arm 177 is provided with acylindrical knurled knob 181 having internal helical threads 182 formedon the interior surface thereof. The cylindrical knob 181 is providedwith an inwardly extending flange 183 which seats in an annular recess184 in the central arm 177 of the y-adapter 176. The knob 181 threadedlyengages exterior helical thread 182 on the proximal extremity of thefirst or outer elongate tubular member 152. The distal extremity ofcentral arm 177 passes through lumen 156 of the outer elongate tubularmember 152 and interior of lumen 166 of the middle elongate tubularmember 162 and is adhesively attached to the proximal extremity 163 ofmiddle elongate tubular member 162 such that the lumen 178 of thecentral arm 177 is in communication with lumen 166 of the third ormiddle tubular member 162. Adhesive attachment of middle tubular member162 to central arm 177 prevents axial movement and rotation of tubularmember 162 with respect to y-adapter 176 when cylindrical knob 181 isrotated, engaging external threads 182 of the proximal extremity 153 ofouter elongate tubular member 152 and causing axial movement of thedistal extremity 154 of outer tubular member 162 with respect to distalextremity 164 of middle elongate tubular member 162.

An externally threaded cylindrical member 196 is secured surroundingarea intermediate the ends of a guide member 197 and is formed of asuitable material such as stainless steel by suitable means such as anadhesive. The guide member 197 extends through a passage 198 provided inthe central arm 177 and is secured to the proximal extremity 158 of thesecond or inner flexible elongate tubular member 157 by suitable meanssuch as an adhesive. A knurled knob 201 having internal threadsthreadedly engages the cylindrical member 196 and is mounted in a fixedaxial position on the central arm 177 and is rotatable therewith tocause axial movement of the second or inner flexible elongate tubularmember 157. An upstanding pin 206 is provided on the guide member 197and extends radially therefrom through an elongate slot 207 formed inthe central arm 177 of the y-adapter 176. The slot 207 is provided withcircumferentially spaced apart parallel elongate portions 207a and 207bwhich are adjoined by an intermediate portion 207c which extends atright angles between the same. Indicia 209 are provided alongside theslot 207 and serve to indicate various positions of the second or innerflexible elongate tubular member 157.

As can be seen and as hereinafter described, the vascular dilatationdevice 151 is particularly adapted for use in dilatation in the mannerhereinbefore described with the previous embodiments but also has thecapability when desired to disengage the flexible cylindrical dilatationmember 31 so that it can self expand and remain in the dilated stenosisso that it can serve as a permanent stent.

Assuming that the flexible cylindrical dilatation member 31 has itsproximal and distal extremities 32 and 33 frictionally engaged ashereinbefore described, the flexible cylindrical dilatation member 31can be moved to a fully extended position by rotating the knurled knob201 to cause the distal extremity 159 of the second or inner flexibleelongate tubular member 151 to be moved away from the distal extremity154 of the first or outer flexible elongate tubular member 152 so as topresent the lowest possible profile for introduction of the vasculardilatation device into the vasculature of the patient in the mannerhereinbefore described. Typically, the guide wire 12 is advanced throughthe stenosis after which the distal extremity 159 of the second or innerflexible elongate tubular member 157 is advanced through the stenosisuntil it is distal of the stenosis and with the distal extremity 154 ofthe first or outer flexible elongate tubular member 152 being proximalof the stenosis. Dilatation can then be carried out by adjustment of theknurled knob 203 by rotating it in an opposite direction to cause thedistal extremity 159 to be brought into closer proximity to the distalextremity 154 to cause radial expansion of the flexible cylindricaldilatation member 31 as hereinbefore described and to cause dilation ofthe stenosis or obstruction in the vessel of the patient. During thisdilatation as hereinbefore described, blood can readily flow through theopen interstices 37 of the proximal and distal extremities 32 and 33 ofthe flexible cylindrical dilatation member 31 to prevent ischemia ashereinbefore described.

After the desired dilatation has been accomplished and it is desired toleave the flexible cylindrical dilatation member 31 in the stenosis, itcan be released from the vascular dilatation device 351 in the followingmanner. While holding the vascular dilatation device 151 stationary inthe patient's vessel, the knob 201 can be rotated to move the distalextremity 159 of the second or inner flexible elongate tubular member157 to cause elongation of the flexible cylindrical dilatation member31. This rotation of knob 203 with distal movement of distal extremity159 of inner tubular member 157 is accompanied by axial distal movementof upstanding pin 206 provided on guide member 197 through slot portion207b until the pin approximates slot portion 207c at right angles toslot portion 207b and pin 206 is prevented from any further axialmovement. This position of pin 206 at the intersection of slot portions207b and 207c corresponds to the distance between the distal extremity159 of inner tubular member 157 and distal extremity 154 of outertubular member 152 equaling the elongation limit of flexible cylindricaldilatation member 31. Pin 206 may now be manually displaced along slotportion 207c until it aligns with slot portion 207a. Further advancementof pin 206 along slot portion 207a is now possible by rotation of knob201 and further advancement of guide member 197 and increase in axialdistance between the distal extremity 159 of inner tubular member 157and the distal extremity 154 of outer tubular member 152. Continuedrotation of the knob 201 causes the distal extremity 33 of the flexiblecylindrical dilatation member 31 to be released from between the collar171 and the outer surface of the second or inner flexible elongatetubular member 157. Upon release, the distal extremity 33 of theflexible cylindrical dilatation member 31 will self expand and open toan increased diameter. Thereafter, the proximal extremity 32 of theflexible cylindrical dilatation member 31 is released by rotating thecylindrical knob 181 to cause the first or outer flexible elongatetubular member 152 to be retracted with respect to the stationary thirdor middle flexible elongate tubular member 162. This rotation iscontinued until the proximal extremity 32 is released permitting it alsoto self expand so that the flexible cylindrical dilatation member 31 isfree within the confines of the stenosis and permitting it to expand toengage the stenosis and to serve as a permanent stent within thestenosis.

The remaining part of the vascular dilatation device 151 can now beremoved by retraction of the same. This can be readily accomplishedsince the distal extremity 33 of the flexible cylindrical dilatationmember 31 has expanded, the collar 171 and the distal extremity 159 ofthe second or inner flexible elongate tubular member 157 can beretracted therethrough. The collar 171 can then pass through theexpanded proximal extremity 32 and be retracted along with the middleand outer flexible elongate tubular members 162 and 152 after which theguiding catheter can be removed and the puncture site sutured in anappropriate manner.

Thus it can be seen that the vascular dilatation device 151, in additionto serving as a dilatation device also serves as a stent placementdevice.

Another embodiment of a vascular dilatation device 221 incorporating thepresent invention is shown in FIGS. 14-19. As shown therein, the device221 consists of a flexible elongate tubular member 222 having proximaland distal extremities 223 and 224. The flexible elongate tubular member222 can be formed out of a suitable material such as a polyethylene or apolyimide.

A lumen 226 extends from the proximal extremity 223 to the distalextremity 224 and has a size which is the same as in the first or outerflexible elongate tubular member 12 hereinbefore described in connectionwith the previous embodiments. Thus, it can have a suitable size as forexample 5-French. A second or inner flexible elongate tubular member 231is provided which is slidably and coaxially disposed within the lumen226. It is provided with proximal and distal extremities 232 and 233with a lumen 234 extending from the proximal extremity 232 to the distalextremity 233. In the present embodiment of the invention, the innerflexible elongate tubular member 231 serves as a support member. Theflexible elongate tubular member 231 is formed of three portions 231a,231b and 231c with the first portion 231a being at the proximalextremity 232 and the second portion 231b extending from the proximalextremity 232 to the near distal extremity 233. The portion 231a isformed of a hypotube having an outside diameter of 0.010" to 0.042" andan inside diameter of 0.012" to 0.030" to provide a wall thickness of0.002" to 0.010". The portion 231a has a suitable length as for example10-30 centimeters. The second portion 231b can be formed so that it hasan outside diameter of 0.016" to 0.042" and an inside diameter of 0.012"to 0.030" to provide a wall thickness of 0.002" to 0.010". Thus it canbe seen that the portion 231a has a greater wall thickness and providesadditional stiffness and rigidity. A guide wire 26 of the typehereinbefore described is slidably disposed in the lumen 234. The lumen234 in the flexible elongate tubular support member 231 is sized so thatit can readily accommodate the guide wire 26. Thus, if a guide wirehaving a size 0.014" is used, the lumen 226 should have a diameter whichis greater than 0.016" to 0.018".

The third portion 231c of the flexible elongate tubular support member231 is formed of a suitable material such as plastic, as for example apolyimide. It has a suitable length, as for example from 20-40centimeters and preferably a length of approximately 30 centimeters. Theportion 231c is bonded to the distal extremity of the portion 231b bysuitable means such as an adhesive. In order to increase the pushabilityof the portion 231c of the flexible elongate tubular member 231 whileretaining its flexibility, a coil spring 236 is embedded within theplastic forming the portion 231c. The coil spring 236 is provided with aplurality of turns 237 as shown in detail in FIG. 19, which preferablyare immediately adjacent or in apposition to each other to provide formaximum pushability. The coil spring 236 should extend at leastthroughout the length of the flexible cylindrical dilatation member 241mounted coaxially thereover as hereinafter described. In addition, asshown the coil spring 236 can extend the entire length of the portion231c. The coil spring 236 is carried by the portion 231c and preferablycan be embedded or encapsulated within plastic 238 of the same typeforming the tubular support member 231. Such embedding of the coilspring 236 prevents uncoiling of the coil elements or turns 237 andelongation of the flexible elongate tubular member 231 upon retractionof the inner elongate tubular member 231 into the outer elongate tubularmember 226 with decrease in distance between proximal and distal ends ofthe flexible cylindrical dilatation member 241. Alternatively, as shownin FIG. 20, a braided member 238 may be substituted for the coil spring236 and also encapsulated or embedded with the plastic forming portion231c. Such encapsulation also prevents elongation of portion 231c uponretraction of the flexible elongate tubular support member 231 into theouter elongate tubular member 226. The metal braid 238 formed of asuitable material such as stainless steel wires 239 of a suitablediameter ranging from 0.001" to 0.003" can be used to form the mesh forthe braided member 238. The braided member 238 increases the pushabilityof the portion 231c of the inner flexible elongate tubular member 231and also prevents substantial elongation of the inner flexible elongatetubular member 231.

A safety ribbon 241 is provided within the inner flexible tubular member231 to prevent elongation of the portion 231c of the inner flexibleelongate tubular member 231 and extends from the distal extremity Ofportion 231b to the distal extremity of portion 231c. The safety ribbon241 can be formed of a suitable material such as stainless steel havinga diameter area of 0.002" to 0.004". The safety ribbon 241 is disposedadjacent the portion 231c of the flexible elongate tubular member 231,and preferably as shown extends interiorly of the portion 231c in thelumen 234 and has its distal extremity secured to the distal extremityof the portion 231c by solder 242. The safety ribbon 241 has itsproximal extremity secured to the distal extremity of the portion 231bof the inner flexible elongate tubular member 231 by the use of solder243 (see FIG. 14).

A flexible cylindrical dilatation member 246 is provided with proximaland distal extremities 247 and 248 as shown in FIG. 17 and is disposedcoaxially on the portion 231 of the inner flexible elongate tubularmember 231. The flexible cylindrical dilatation member 246 isconstructed in a manner similar to the flexible cylindrical dilatationmember 31 hereinbefore described and is provided with a plurality offlexible elongate elements or filaments 251 in which a plurality ofelements 251 have a first common direction of rotation about the centralaxis as shown in FIG. 14 and are axially displaced relative to eachother and cross over a further plurality of the flexible elongateelements 251 also axially displaced relative to each other but having asecond common direction of rotation opposite to that of the firstdirection of rotation to form a double helix, braided or mesh-likeflexible cylindrical dilatation member 246 with the crossing of theflexible elongate elements 251 occurring in the area of contact betweenthe flexible elongate elements 251 to form openings or interstices 252therebetween. The solder 242 used for securing the safety ribbon 238 tothe coil spring 236 is also used for securing the distal extremity 248of the cylindrical dilatation member 246 to the distal extremity of theinner flexible elongate tubular member 231. A sleeve 253 of heat shrinktubing covers the solder 242.

In order to increase the radial forces generated by the flexiblecylindrical dilatation member 246, it has been found that it isdesirable to provide undulations 256 in which there is an undulation 256present at each cross-over point of the filaments 251. Thus, as shown inFIG. 21, which is a fragmentary view of the cylindrical dilatationmember 246 shown in FIG. 17, an undulation 256 is provided in each ofthe plurality of flexible elongate elements 251 having a first directionof rotation at every other cross-over point with the plurality offlexible elongate elements having a second common direction of rotationabout the central axis and wherein the undulations in the adjacentelements 251 are offset by one cross-over point so that in the resultingmesh or braid construction, the undulations 256 in one of the elements251 having a first direction of rotation overlies every other cross-overpoint of the element 251 having a second direction of rotation and,conversely, every element 251 having a second direction of rotation hasan undulation 256 therein at every other cross-over point of theelements 251 having a first direction of rotation. These undulations 256can be in the form of obtuse angle bends having straight portionsextending from both sides of the bend, or alternatively can be in theform of arcuate portions having a diameter corresponding generally tothe diameter of the elements 251. Thus, it can be seen that theundulations 251 make it possible for one of the elements 251 to supportthe other of the elements at each cross-over point, thereby preventingslippage of the elements 251 with respect to each other and therebycausing greater radial forces to be applied when the flexiblecylindrical dilatation member 246 is expanded as hereinafter described.

The flexible cylindrical dilatation member 246 is comprised of 21-64individual elements 251 formed of 0.020 millimeter diameter wire of asuitable metal such as stainless steel helically wound around alongitudinal central axis. The helices are wound in opposite directions.Stretching or elongation of the flexible cylindrical dilatation member246 results in a reduction in diameter of the flexible cylindricaldilatation member 246. Mechanical fixation of the proximal and distalextremities 247 and 248 of the flexible cylindrical dilatation member246 holds these extremities in reduced diameter configurations. Thepositions of the elements 251 in these extremities cannot change inrelation to each other. Therefore, the crossing angles of the elements251 remain constant. Shortening of the flexible cylindrical dilatationmember 246 with the ends fixed results in the formation of a cylindricalcenter section of great rigidity with the elements 251 in closeapposition to each other. The tapered proximal and distal extremities ofthe flexible cylindrical dilatation member 246 causes the stresses onthe individual elements 251 to be balanced. Since the proximal anddistal extremities 247 and 248 are held in constant tapered positions,the interstices 252 between the elements 251 are maintained allowingblood to flow into and out of the cylindrical center section when theflexible cylindrical dilatation member 246 is shortened as shown in FIG.22. Shortening of the flexible cylindrical dilatation member or spring246 results in a significant increase in the metal density per unitlength in the center portion of the flexible cylindrical dilatationmember 246 while the metal density at the ends is relatively constant.This increase in metal density in the center section results insignificant radial force generation as the elements 251 are compressedin a longitudinal direction into preformed diameters.

Use of the helically wound coil spring 236 or the braid 238 which serveswith or as part of the inner elongate tubular member 231 and coaxiallydisposed within the flexible cylindrical dilatation member 246 providesgreatly improved pushability and axial column strength for causingelongation of the cylindrical dilatation member 246 while providing thedesired flexibility so that tortuous curves can be negotiated duringdeployment of the vascular dilatation device 221. The portion 231c ofthe flexible elongate tubular member 231, and particularly within theflexible cylindrical dilatation member 246, has a relatively smalldiameter so that it does not adversely affect the stenosis crossingprofile for the vascular dilatation device 221. The use of the inner orsafety ribbon 241 prevents undue elongation and unwinding of the coilspring 236 forming a part of portion 231c of the flexible elongatetubular member 231 when the flexible cylindrical dilatation member 246is lengthened or elongated. The pull or safety ribbon 241 also limitselongation of the flexible cylindrical dilatation member 246 and therebyprevents the elements 251 from being broken off or pulled away from thesolder joints 253.

The proximal extremity 223 of the outer flexible elongate tubular member222 of the vascular dilatation device 221 is provided with control means261 for causing relative movement between the first or outer flexibleelongate tubular member 222 and the second or inner flexible elongatetubular member 231 and can be similar to that hereinbefore described.This control means 261 consists of a fitting 262 which is bonded to theproximal extremity 223 of the outer flexible elongate tubular member222. The fitting 262 is provided with a male Luer fitting 263 removablymated with a female Luer fitting 264 carried by a Y-adapter 266 which isprovided with a central arm 267 and a side arm 268. The side arm 268 isin communication with the lumen 226 of the outer flexible elongatetubular member 222. The inner flexible elongate tubular member 231extends through the central arm 267 of the y-adapter 266. A rotatableknob 269 is provided on the central arm of the y-adapter 266 for forminga fluid-tight seal between the central arm 267 and the portion 231a ofthe inner flexible elongate tubular member 231. A male Luer fitting 271is mounted on the proximal extremity of the portion 231a. The guide wire26 extends through the lumen 234 of the inner flexible elongate tubularmember 231 and extends beyond the distal extremity thereof.

As hereinbefore described, the control means 261 can include means suchas a screw mechanism for causing relative movement between the outerflexible elongate tubular member 222 and the inner flexible elongatetubular member 231.

Operation and use of the vascular dilatation device 221 is substantiallysimilar to that hereinbefore described with respect to the previousembodiments. The vascular dilatation device 221 however has a member offeatures which may be more advantageous in certain medical procedures.Thus in medical procedures where improved pushability and torquabilityis required the use of the metal hypotube for the portion 231b of theflexible elongate tubular member provides additional pushability andtorquability for the catheter facilitating advancement of the vasculardilatation device 221 through more difficult stenoses, particularlywhere additional torquability and pushability are desired. This is alsotrue with the distal extremity of the vascular dilatation device 221 inwhich the inner flexible elongate tubular member 231 has the distalportion 231c thereof that includes the compressed coil spring 236 orbraided member 238 which extends at least through the flexiblecylindrical dilatation member 246 to provide additional pushability forthe flexible cylindrical dilatation member 246 while still retaining thedesired flexibility. Even though improved pushability is provided, thedistal extremity of the vascular dilatation device 221 is still veryflexible permitting it to track tortuosities in the vessels beingnegotiated thereby. Also because of the pushability of the innerflexible elongate tubular member 231, it is possible to obtain maximumextension of the flexible cylindrical dilatation member 246 and therebya minimum diameter to facilitate crossing of a stenosis with very smallopenings therethrough with the vascular dilatation device 221. Thesafety ribbon 241 prevents undue elongation of the inner flexibleelongate tubular member 231. In addition, encapsulation of thecompressed coil spring 236 or braided member 238 also preventselongation of the inner flexible elongate tubular member 231.

When the flexible cylindrical dilatation member 246 is being expanded bydecreasing the length of the same, such as in the manner shown in FIG.21, the diameter of the flexible cylindrical dilatation member isincreased to its maximum size with great rigidity because of theundulations 256 provided in the elements 251 of the flexible cylindricaldilatation member or flexible cylindrical dilatation member 246. Theseundulations 256 aid providing greater radial forces while stillretaining the conical or tapered ends with the open interstices toreadily permit blood to pass through the flexible cylindrical dilatationmember 246 during the time that the flexible cylindrical dilatationmember 246 has been expanded to its maximum diameter to apply maximumradial forces to the stenoses which is being dilated during theprocedure.

From the foregoing, it can be seen that there has been provided avascular dilatation device which can be used in the same manner as aballoon catheter in performing an angioplasty procedure with theoutstanding advantage that blood can continue to flow to the distalblood vessel during the dilatation procedure. This permits a longervessel dilatation without tissue ischemia. Significantly more blood canflow than through a standard perfusion balloon. In addition a perfusionof side branches continues through the flexible cylindrical member.Prolonged drug infusion may also be undertaken with delivery of drugdirected directly to the site of the angioplasty procedure.

I claim:
 1. A vascular dilatation device for enlarging a flow passage inan obstruction in a vessel carrying flowing blood comprising a flexiblecylindrical dilatation member for placement in the flow passage in theobstruction and having first and second ends and an intermediate portionbetween the first and second ends, said flexible cylindrical dilatationmember also having an interior flow passage extending therethrough witha diameter and a longitudinally extending central axis, said diameter ofsaid flow passage being variable with movement of the first and secondends relative to each other along the longitudinally extending centralaxis from a contracted position to an expanded position, said expandedposition permitting blood to flow through the flexible cylindricaldilatation member and means for causing relative axial movement of saidfirst and second ends towards each other from an extended position to acontracted position, said means for causing relative axial movementincluding an outer flexible elongate tubular member having proximal anddistal extremities, said distal extremity of the outer flexible elongatetubular member being secured to the first end of said flexiblecylindrical dilatation member and an inner flexible elongate tubularmember having proximal and distal extremities and disposed between thefirst and second ends of the flexible cylindrical dilatation member,said distal extremity of the inner flexible elongate tubular memberbeing secured to the second end of said flexible cylindrical dilatationmember, said inner flexible elongate tubular member having sufficientrigidity for causing elongation of the cylindrical dilatation member soas to decrease its diameter and cause advancement of the cylindricaldilatation member through the obstruction in the vessel while preventingaxial contraction of the cylindrical dilatation member.
 2. A device asin claim 1 further including a coil spring carried by said innerflexible elongate tubular member, said coil spring having turns whichare in apposition to each other.
 3. A device as in claim 2 wherein saidcoil spring is embedded in the inner flexible elongate tubular member.4. A device as in claim 2 further including a safety ribbon secured tothe inner flexible elongate tubular member and serving to preventelongation of the coil spring at the distal extremity of the innerflexible elongate tubular member.
 5. A device as in claim 1 furtherincluding a braided member embedded in the inner flexible elongatetubular member.
 6. A device as in claim 1 wherein said inner flexibleelongate tubular member is formed of a plastic.
 7. A device as in claim1 for use with a guide wire wherein said inner flexible elongate tubularmember has a lumen extending therethrough, said lumen being sized sothat it is adapted to having the guide wire slidably mounted therein. 8.A vascular dilatation device for enlarging a flow passage in anobstruction in a vessel carrying flowing blood comprising a flexiblecylindrical dilatation member for placement in the flow passage in theobstruction and having first and second ends and an intermediate portionbetween the first and second ends, said flexible cylindrical dilatationmember also having an interior flow passage extending therethrough witha diameter and a longitudinally extending central axis, said diameter ofsaid flow passage being variable with movement of the first and secondends relative to each other along the longitudinally extending centralaxis from a contracted position to an expanded position, said expandedposition permitting blood to flow through the flexible cylindricaldilatation member and means for causing relative axial movement of saidfirst and second ends of the flexible cylindrical dilatation membertowards each other from an extended position to a contracted position,said means for causing relative axial movement including an outerflexible elongate tubular member having proximal and distal extremities,said distal extremity of the outer flexible elongate tubular memberbeing secured to the first end of said flexible cylindrical dilatationmember and an inner flexible elongate tubular support member havingproximal and distal extremities and disposed between the first andsecond ends of the flexible cylindrical dilatation member, said distalextremity of the inner flexible elongate tubular support member beingsecured to the second end of said flexible cylindrical dilatationmember, said inner flexible elongate tubular support member extendingfrom the proximal extremity of the outer flexible elongate tubularmember to a location at least near the distal extremity of the outerflexible elongate tubular member, said inner flexible elongate tubularsupport member having sufficient rigidity for causing elongation of thecylindrical dilatation member so as to decrease its diameter and causeadvancement of the cylindrical dilatation member through the obstructionin the vessel while preventing axial contraction of the cylindricaldilatation member, said inner flexible elongate tubular support memberalso providing increased pushability and torquability to the device. 9.A device as in claim 8 wherein said distal extremity of the innerflexible elongate tubular support member is coupled to the second end ofthe flexible cylindrical dilatation member.
 10. A device as in claim 8further including a coil spring carried by said inner flexible elongatetubular support member, said coil spring having turns which are inapposition to each other.
 11. A device as in claim 8 further including abraided member embedded in the inner flexible elongate tubular supportmember.
 12. A vascular dilatation device for enlarging a flow passage inan obstruction in a vessel carrying flowing blood comprising a flexiblecylindrical dilatation member for placement in the flow passage in theobstruction and having first and second ends and an intermediate portionbetween the first and second ends, said flexible cylindrical dilatationmember having an interior flow passage extending therethrough with adiameter and a longitudinally extending central axis, said diameter ofsaid flow passage being variable with movement of the first and secondends relative to each other along the longitudinally extending centralaxis and means for causing relative axial movement of the first andsecond ends towards each other from an extended position of a decreaseddiameter to a contracted position of an increased diameter, said meansincluding a relatively rigid flexible elongate tubular support memberextending from near the proximal extremity of the outer flexibleelongate tubular member to a region in the distal extremity of the outerflexible elongate tubular member, said flexible elongate tubular supportmember providing increased pushability and torquability to the device.13. A device as in claim 12 wherein at least a portion of said flexibleelongate tubular support member is formed of metal.
 14. A device as inclaim 12 wherein said flexible cylindrical dilatation member is in theform of a dilatation spring comprised of a plurality of flexibleelongate elements extending helically about the longitudinally extendingcentral axis and having first and second common directions of rotationto form a braid with cross-over points, said elements being formed withundulations therein disposed at the cross-over points to inhibitslipping movement of the flexible elements with respect to each otherduring contraction of the flexible cylindrical dilatation member toincrease the radial forces being applied to the obstruction by theflexible cylindrical dilatation member during contraction of theflexible cylindrical dilatation member.
 15. A device as in claim 14wherein the undulations in each of the flexible elongate elements occursat every other cross-over point.
 16. A device as in claim 15 wherein theundulations in one of the flexible elongate elements having the samedirection of rotation and the next adjacent flexible elongate elementhaving the same direction of rotation and having undulations thereinoffset therein by one cross-over point.
 17. A method for enlarging aflow passage extending through an obstruction in a vessel having aninner wall and carrying flowing blood by the use of an expandableflexible cylindrical dilatation member movable between contracted andexpanded positions, moving the expandable flexible cylindricaldilatation member into the flow passage in the obstruction whilepreventing contraction of the flexible cylindrical dilatation member,expanding the flexible cylindrical dilatation member by sufficientlyincreasing its radial rigidity to compress the obstruction against theinner wall of the vessel to enlarge the flow passage in the obstructionin the vessel while permitting blood to flow through the expandableflexible cylindrical dilatation member during the time the expandableflexible cylindrical dilatation member is in an expanded condition tothereby maintain blood flow in the vessel.